repo: change the returning value of repo.diff

repo.diff now returns list of dictionaries for each file/directory change

dvc/command/diff.py

@@ -1,5 +1,9 @@
 from __future__ import unicode_literals
 
+import humanize
+import inflect
+
+
 import dvc.logger as logger
 from dvc.exceptions import DvcException
 from dvc.command.base import CmdBase
@@ -7,7 +11,68 @@ from dvc.utils.collections import compact
 
 
 class CmdDiff(CmdBase):
-    def _show(self, msg):
+    def _print_size(self, size):
+        if size < 0:
+            change = "decreased by {}"
+        elif size > 0:
+            change = "increased by {}"
+        else:
+            change = "not changed"
+        natur_size = humanize.naturalsize(abs(size))
+        return change.format(natur_size)
+
+    def _show(self, diff_dct):
+        engine = inflect.engine()
+        msg = "dvc diff from {} to {}".format(
+            diff_dct["a_ref"], diff_dct["b_ref"]
+        )
+        if diff_dct.get("equal"):
+            logger.info(msg)
+            return
+        for dct in diff_dct["diffs"]:
+            msg += "\n\ndiff for '{}' \n".format(dct["target"])
+            if dct.get("old_file"):
+                msg += "-{} with md5 {}\n".format(
+                    dct["old_file"], dct["old_checksum"]
+                )
+            if dct.get("new_file"):
+                msg += "+{} with md5 {}\n".format(
+                    dct["new_file"], dct["new_checksum"]
+                )
+            msg += "\n"
+            if dct.get("is_dir"):
+                msg += "{} {} not changed, ".format(
+                    dct["ident"], engine.plural("file", dct["ident"])
+                )
+                msg += "{} {} modified, ".format(
+                    dct["changes"], engine.plural("file", dct["changes"])
+                )
+                msg += "{} {} added, ".format(
+                    dct["new"], engine.plural("file", dct["new"])
+                )
+                msg += "{} {} deleted, ".format(
+                    dct["del"], engine.plural("file", dct["del"])
+                )
+                msg += "size was {}".format(self._print_size(dct["size_diff"]))
+            else:
+                if (
+                    dct.get("old_file")
+                    and dct.get("new_file")
+                    and dct["size_diff"] == 0
+                ):
+                    msg += "file size was not changed"
+                elif dct.get("new_file"):
+                    msg += "added file with size {}".format(
+                        humanize.naturalsize(dct["size_diff"])
+                    )
+                elif dct.get("old_file"):
+                    msg += "deleted file with size {}".format(
+                        humanize.naturalsize(abs(dct["size_diff"]))
+                    )
+                else:
+                    msg += "file was modified, file size {}".format(
+                        self._print_size(dct["size_diff"])
+                    )
         logger.info(msg)
 
     def run(self):